Podcast
Questions and Answers
What happens to the concentration of hydronium ions (H3O+) when a common ion is added to a solution?
What happens to the concentration of hydronium ions (H3O+) when a common ion is added to a solution?
Which of the following statements about the common ion effect is true?
Which of the following statements about the common ion effect is true?
In the example provided, which ion acts as the common ion when formic acid is added to sodium formate?
In the example provided, which ion acts as the common ion when formic acid is added to sodium formate?
Which principle is used to predict the shift in equilibrium due to the common ion effect?
Which principle is used to predict the shift in equilibrium due to the common ion effect?
Signup and view all the answers
What is the expected effect on pH when formic acid is added to pure water without a common ion?
What is the expected effect on pH when formic acid is added to pure water without a common ion?
Signup and view all the answers
What effect does the presence of a common ion have on the dissociation of weak acids in solution?
What effect does the presence of a common ion have on the dissociation of weak acids in solution?
Signup and view all the answers
In the context of the common ion effect, what role do spectator ions play?
In the context of the common ion effect, what role do spectator ions play?
Signup and view all the answers
How does the common ion effect influence the calculation of pH in solutions?
How does the common ion effect influence the calculation of pH in solutions?
Signup and view all the answers
The addition of formic acid to a sodium formate solution results in a higher concentration of hydronium ions compared to pure water.
The addition of formic acid to a sodium formate solution results in a higher concentration of hydronium ions compared to pure water.
Signup and view all the answers
Sodium ions (Na+) influence the pH of the solution when formic acid is added to sodium formate.
Sodium ions (Na+) influence the pH of the solution when formic acid is added to sodium formate.
Signup and view all the answers
Le Châtelier's principle explains the shift in equilibrium that occurs with the introduction of a common ion.
Le Châtelier's principle explains the shift in equilibrium that occurs with the introduction of a common ion.
Signup and view all the answers
The calculated pH of a solution with a common ion is lower than the pH when formic acid is added to pure water.
The calculated pH of a solution with a common ion is lower than the pH when formic acid is added to pure water.
Signup and view all the answers
A solution with an initial concentration of 0.1 molar formate ions will demonstrate the common ion effect when formic acid is added.
A solution with an initial concentration of 0.1 molar formate ions will demonstrate the common ion effect when formic acid is added.
Signup and view all the answers
Match the terms related to the common ion effect with their corresponding definitions:
Match the terms related to the common ion effect with their corresponding definitions:
Signup and view all the answers
Match the acids or bases with their relevant examples in relation to the common ion effect:
Match the acids or bases with their relevant examples in relation to the common ion effect:
Signup and view all the answers
Match the following scenarios with their outcomes regarding pH changes:
Match the following scenarios with their outcomes regarding pH changes:
Signup and view all the answers
Match the terms with their effects on hydronium ion concentration in a solution:
Match the terms with their effects on hydronium ion concentration in a solution:
Signup and view all the answers
Match the components involved in the pH calculation with their roles:
Match the components involved in the pH calculation with their roles:
Signup and view all the answers
Study Notes
Common Ion Effect
- The common ion effect occurs when an acid or base is added to a solution already containing an ion present in the acid or base.
- This differs from adding an acid or base to pure water, as the initial concentration of the common ion is not zero.
- The presence of a common ion shifts the reaction equilibrium to the left, decreasing the hydronium ion (H3O+) concentration.
- This leads to a higher pH (more basic solution).
- Le Chatelier's Principle explains this shift: adding a common ion on the product side of the equilibrium drives the reaction backward, favoring the formation of reactants.
The Impact of the Common Ion
- A common ion lowers the hydronium ion (H3O+) concentration and raises the solution's pH.
- This equilibrium shift, towards reactants, is predicted by Le Chatelier's principle.
- Adding a common ion stresses the equilibrium, prompting a shift towards reactants, reducing the common ion's concentration.
Example Calculation: Formic Acid and Sodium Formate
- Formic acid (HCOOH) is added to a sodium formate (HCOONa) solution.
- Sodium formate completely dissociates, creating formate ions (HCOO-) and sodium ions (Na+). Sodium ions are spectator ions.
- The initial concentration of formate ions is crucial and is not zero.
- The equilibrium of the formic acid dissociation reaction shifts to the left, favoring the formation of undissociated formic acid, due to the common ion.
- This reaction is represented as:
HCOOH (aq) + H2O (l) <=> H3O+ (aq) + HCOO- (aq)
- The presence of the common ion (formate ion) lowers the hydronium ion concentration and raises the pH compared to adding formic acid to pure water.
- Calculation, incorporating the initial common ion concentration and Ka value, yields a different pH (e.g., 3.27) compared to the pH of a solution without the common ion (e.g., 2.13).
- This difference is a direct result of the common ion effect.
- The initial concentration of the common ion is included in the ICE table.
Predicting pH Changes
- Le Chatelier's principle predicts the common ion effect: stressing an equilibrium system by adding a common ion results in a shift towards reactants.
- This results in a reduced hydronium ion concentration and an increased pH.
Conclusion
- The common ion effect is crucial in acid-base equilibrium scenarios.
- Its presence significantly impacts solution pH, especially in solutions already containing common ions.
- The formic acid/sodium formate example demonstrates how the common ion effect influences pH calculations and values.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz explores the common ion effect and its impact on acid-base equilibria. It explains how the presence of a common ion alters the pH of a solution and includes calculations involving formic acid and sodium formate. Test your understanding of these chemical concepts!
